Dark Energy : Cosmologists have known since the 1920's that the universe is expanding, its galaxies racing away from one another in all directions. Just a few years ago, however, a study of very distant supernovas added a confounding twist: the cosmic expansion is speeding up. Distant galaxies are racing outward at faster velocities. And that doesn't make sense. Gravity is supposed to slow the cosmic expansion -if not to an outright halt (eventually), then at least to a steady pace. Yet here we are, picking up speed. What's going on?
To explain this conundrum, cosmologists have postulated that a strange, previously undescribed repulsive force, which they call dark energy, is at work, counteracting gravity and pushing galaxies apart at an accelerating rate. That's what dark energy does, anyway; what dark energy is. .. well, that's still unclear. this year, astronomers and astrophysicists uncovered convincing new data to confirm that dark energy, whatever it is exactly, really exists. In September, a team of University of Chicago astronomers found evidence of dark energy in subtle fluctuations in the cosmic microwave background - a haze of microwave energy that formed just 400,000 years after the Big Bang and still pervades the universe. In November, a separate team, studying how galaxies bend the light from distant quasars behind them, likewise detected the fingerprints of dark energy. And not only is dark energy real, but the new experiments indicate it's also running amok. Until a couple billion years ago, dark energy was a relatively minor force; now it comprises two-thirds of all the energy in the universe.
Dark energy marks the coming of age of cosmology. The latest telescopes and technology now enable researchers to probe the oldest structures in the universe, to conduct experiments on - and confirm or refute predictions about - the beginning of time itself. Astronomy, astrophysics, particle physics and theory have merged into a true, hard science. Einstein gave us this idea in 1915….From now on Physics must accept this new force!